1. Field of the Invention
The present invention relates to circuit configuration technology and more particularly, to a circuit configuration for touch panel controller integrated circuit (“IC”), comprising a plurality of processing units arranged in one same direction in a parallel manner, which enables differences in environmental conditions in exposure graphic definition and etch rate to be minimized so that better circuit component process uniformity and a high level of sensing accuracy can be obtained.
2. Description of the Related Art
At the present time, screen sizes of touch-enabled devices grow larger. In order to obtain better sensing effects, a high sensing point density must be maintained. Increasing the sensing point density relatively increases the number of signal transmission channels. In consumer electronic devices, a touch panel is incorporated into a display screen. To meet consumer demand for visual enjoyment and spatial utilization, consumer electronic products are commonly designed to provide a narrow bezel, limiting the installation space for circuit board and related control IC. Therefore, the length-to-width ratio of a controller IC package substrate must be increased to fit a narrow bezel design. However, it is complicated to design a circuit configuration for touch panel controller IC under the restrictions of limited installation space, signal transmission channel requirement and chip electrode arrangement to match pin arrangement.
FIG. 4 illustrates circuit configuration for touch panel controller IC according to the prior art. According to this prior art design, the circuit configuration comprises a substrate A, and a chip B mounted on the substrate A. The chip B comprises a plurality of processing units B1 classified as first processing units B11 and second processing units B12. The first processing units B11 are arranged in a transverse row at the center area of the chip B, and respectively extend in longitudinal direction. The second processing units B12 are arranged in two longitudinal rows at opposing left and right sides relative to the first processing units B11, and respectively extend in transverse direction. The processing units B1 are respectively electrically connected to respective input/output units B2, which are respectively electrically connected to equally spaced electric contacts B3 that are respectively electrically connected to respective electrode pins C at the border area of the substrate A around the chip B by respective lead wires B31. Thus, the electrode pins C allow input of sensing signals from an external touch screen into the processing units B1 for processing.
In actual application, the aforesaid prior art circuit configuration for touch panel controller IC has drawbacks as follows:
1. Because the first processing units B11 and the second processing units B12 are arranged at different locations in different directions, differences in environmental conditions (such as angle or distance) in exposure graphic definition and etch rate during fabrication of the touch-panel controller IC are significant, in consequence, the variation between the first processing units B11 and the second processing units B12 after fabrication can be significant, affecting sensing accuracy.
2. Because the first processing units B11 and the second processing units B12 are arranged at different locations in different directions, the electric contacts B3 corresponding to the first processing units B11 are arranged close to one another, however, the respective electrode pins C are arranged at a relatively larger pitch. During wire bonding, the lead wires B31 are straightly extended from the electric contacts B3 to the electrode pins C. Due to narrow bezel design, the width of the substrate A is narrowed. Thus, as shown in FIG. 5, most lead wires B31 have a large skew angle. After being bonded, the lead wires B31 are disposed in proximity to respective adjacent electric contacts B3 or electrode pins C. Therefore, some lead wires B31 may be erroneously pressed over adjacent electric contacts B3 or electrode pins C, causing a short circuit and resulting in defective products and lowering the yield.